EPA administrator Lisa Jackson has left the building

We knew this one was coming, but now it’s official: Lisa Jackson, President Obama’s long-embattled administrator of the Environmental Protection Agency, is leaving her post.

Jackson served for four years as lead environmental regulator for the Obama administration, taking innumerable volleys of criticism from all directions. Serious environmentalists felt she caved too regularly to White House-driven compromises, allowing the climate to become a footnote and essential initiatives to be watered down. Meanwhile, the Tea Party right set her up as a job-killing bogeyperson and marshal of a “war on coal.” (Green types only wished that war was real.)

As the first African American EPA administrator, Jackson brought a more inclusive approach to her environmental work — moving both her agency and the national public far beyond old green stereotypes. The achievements of Jackson’s tenure were real: major improvements in automobile emissions standards, important new controls on mercury in power-plant fumes, and the first-ever federal ruling that greenhouse gases should be classed as pollutants.

And yet no one who is conscious of the climate crisis can fail to see the last four years as, fundamentally, a failure where it most counts — a critical, fleeting, now-missed chance to jam open a closing window of opportunity and alter our global-warming course. Early in Obama’s first term, the White House and a then-Democratic Congress took one futile run at a watered-down cap-and-trade measure, then played dead on the issue. Obama barely mentioned the climate during his reelection campaign. Prospects for stronger action remain dim.

When Grist interviewed Jackson last summer, we asked her what headline she’d write over her administration’s record on climate issues. She joked about not being good at keeping her language short and sweet, then came out with:

“In accordance with the law, we moved forward with sensible, cost-effective steps at the federal level on climate, using the Clean Air Act.” And I would have a second sentence — see, I can’t write headlines! But it would be something like, “The progress at state and local levels, combined with the federal level, does not obviate the need” — you can’t use obviate, it’s above fifth-grade level! — “does not obviate the need for federal legislation to address this incredibly important challenge for this and future generations.”